Although scientists will depend heavily on visual images for
their Martian studies, a third instrument on Surveyor will image
the planet in regions of the energy spectrum that humans cannot
see. This instrument, called TES, will conduct infrared scans of
the planet. On a color chart, infrared represents the region that
would take on an extremely deep red hue if the human eye could
see it. Scientists frequently refer to infrared emissions as heat
or thermal energy.

TES works on the concept that different types of compounds
will take on different temperatures when exposed to the same
amount of sunlight. For example, water in the ocean always
remains cooler than the hot sand on the beach. The thermal data
radioed back to Earth from TES will allow scientists to determine
the general mineral composition of patches of ground as small as
9.0 square kilometers (3.5 square miles) in area. Scientists will
gather this type of data over many days in order to conduct a
planet-wide mineral survey of Mars. In addition, TES will also
scan the Martian atmosphere to provide data for the study of the
clouds and weather.

Many scientists hope that TES will ultimately yield clues
into the location of clays containing carbonate minerals.
Although no liquid water exists on Mars today, carbonate deposits
might indicate areas that could have been shorelines long ago in
Martian history. Future missions to Mars might begin their search
for fossil remains of life in areas identified by TES data.